The invention relates generally to trimming and more specifically to functional trimming and/or component trimming on a substrate having components that are surface-mounted on the substrate and/or integrated in the substrate.
Laser trimming of printed circuit patterns on the surface of a ceramic substrate is known per se.
In some applications, there are strict requirements on the physical dimensions of the substrate. This has led to a design of so called LTCC substrates (Low Temperature Cofired Ceramic substrates) where some components such as resistors, inductors and capacitors are integrated on different layers of the substrate at the same time as there are surface-mounted components mounted on the surface of the substrate.
From JP Patent Abstracts Nos. JP 02052494 A and JP 60194556 A, it is known to make a hole or a window in multilayer substrates in order to trim a component integrated on a layer in the substrate. The problem with making a hole or a window in the top layer is that too large an area is lost on the top layer where the surface space is very restricted.
The object of the invention is to enable trimming on a multilayer substrate where there are very strict requirements on the physical dimensions of the substrate and especially the top surface, without having to make holes or windows in the substrate in order to free part of the component to be trimmed.
This is attained in accordance with the invention in that a trimmable structure connected to the component to be trimmed, irrespective of whether the component is surface-mounted or integrated in the substrate, is provided on the surface of the substrate for each component to be trimmed.
Both functional trimming and component trimming can be accomplished in this way.